The invention relates more particularly to a motor vehicle disk brake of the type described and shown in French patent application FR-A1-3004500, which includes:                a brake disk that lies in a plane transverse to an axially oriented axis of rotation of the disk;        a support fixed relative to a chassis of the vehicle,        at least one brake shoe which includes a friction lining a transverse friction face of which cooperates with an associated braking track of the disk, the brake shoe being mounted to slide axially in the support between an active front position in which the friction face bears against the associated annular track of the disk and an inactive rear position in which the friction face is spaced axially from the associated annular track of the disk by a particular operating clearance,        at least one spring for elastically returning the brake shoe to its inactive position, which is disposed between the brake shoe and the support, for example.        
In a disk brake, the sliding of the brake shoes toward their active position is driven by a piston. The two brake shoes then clamp the disk strongly to slow down its rotation. The braking operation is therefore an active operation.
The brake shoes are pushed back toward their inactive position by the rotating disk. This is therefore a passive operation.
However, it can happen that the disk does not push the brake shoes back with sufficient force to separate them from the disk by a sufficient distance. For example, this can occur if the sliding of the brake shoes is of insufficient quality or even jammed, or if the design creates “restitution”.
Although the brake shoes are no longer clamped actively against the disk, each of the annular tracks of the latter nevertheless rubs at all times against the friction lining carried by the associated brake shoe. The friction linings are then subjected to premature non-functional wear.
Moreover, this permanent friction is liable to cause heating that is harmful for some members of the disk brake.
This permanent friction also generates a residual torque that opposes the rotation of the disk. This increases the fuel consumption of the vehicle as well as degrading the performance of the vehicle.
To solve these problems of wear and heating, the aforementioned document proposes a disk brake in which the return spring includes means for compensating wear play of the friction lining of the brake shoe that deform plastically if the travel of the brake shoe to its active position is greater than said predetermined operating clearance.
To this end, the return spring includes at least one axially oriented section that is elastically deformable in traction between a rest state and a state of maximum elongation the value of which is equal to the particular operating clearance, the spring including at least one section deformable plastically by an axial traction force, forming said wear play compensating means, this plastically deformable section being conformed so as to be stretched plastically if the travel of the brake shoe to its active position is greater than the particular operating clearance.
In accordance with the embodiment proposed in this document, the plastically deformable section is formed by accordion folding a section of the blade.
In accordance with another design described and shown in the document WO-A1-2014/029840, the return spring includes, successively:                a portion for fixing the return spring to the disk brake;        a second rigid branch a proximal end of which is connected to the fixing portion by a first bend plastically deformable about a first deformation axis orthogonal to the axial direction of movement of the brake shoe and parallel to the plane in which the second rigid branch lies; and        a third rigid branch a proximal end of which is connected to a distal end of the second rigid branch by a second bend plastically deformable about a second deformation axis parallel to the first deformation axis.        
The invention aims to improve the design and the performance of such return springs and notably to regularize the performance of the spring in terms of elasticity and the value of the elastic return force produced by the spring and to regularize the direct or indirect cooperation of the spring with an associated portion of the brake shoe.